Welcome to Zoology World

balindrakumar033@gmail.com   25/11/2017,Saturday

WELCOME TO ZOOLOGY WORLD

The science or study of animal life. Together with botany, the study of plant life, it forms the science of biology. Zoology is such a vast subject that most zoologists specialize or focus on the study of particular organisms or taxonomic groups. tion of animals.

Heamal arch:

It surrounds the heamal canal which allows the blood vessels of the tail region to pass. It may be produced into a heamal spine below e.g, in fishes.The heamal arch of the caudal vertebrae of reptiles is called chevron bone.It is usually Y-shaped.

Centrum:

The part of vertebra attached to second by centrum.On the basis of centrum vertebrae may be following type-

(i)Procoelous-vertebrae:

Anterior end is concave and posterior end is convex.e.g, 2nd to 7th vertebra of frog,Reptile(Lizard).

(ii)Ophisthocoelous vertebrae:

Anterior end is convex and posterior end is concave. e.g., fishes,snake, and crocodile only.

(iii)Heterocoelous vertebrae:

Anteriorly convex from dorsal to ventral and cancave from side to side.On posterior side concave from dorsal to ventral and convex from side to side(saddle shaped). e.g.,Birds.

(iv)Acoelous vertebrae:

Also know as Amphiplatyon.No cavity in centrum so centrum is flat.e.g.,Mammals (man,Rabbit).

(v)Amphicoelous vertebrae:

Cavity present on both side of centrum.e.g.,VIIIth vertebra of frog.All vertebrae of scolidon (Dog fish).

(vi)Amphidicondylar (Biconvex):

Biconvex,condyle on both side.e.g.,IXth vertebra of frog.

Vertebral column of man:

Made up of pieces of bones known as vertebrae.Vertebrae of man are acoelous ie.Centerum is flat and without cavity(Amphiplatyon). Vertebral column is also known as spinal column or backbone.

types of centrum

(1)Atlas vertebra:

(i) First cervical vertebra.

(ii)Body is formed of vertebral arch transverse process.

(iii)It supports the globe of the head like the earth by the atlas(super man).

(iv)Centrum is absent.

(v)Neural spine absent.

(vi)Transverse process are long with transverse foramen.

(2)Axis vertebra

(i)Second cervical vertebra.

(ii)Centrum acoelous.

(iii)Odontoid process or dens present,which is modified centrum of Atlas.

(iv) It is pivot for rotation of atlas and head around adontoid process.Transverse

(3)Typical cervical vertebra

(i)Long neural spine.

(ii)Centrum acoelus.

(iii)Transverse process are large.

(iv)Vertebrarteal canal present.

(v)Vertebrarteal canals also known as foramina transversaria.

(4)Thoracic vertebra

(i)Centrum acoelus.

(ii)Neural canal is formed by union of two neural arches.

(iii)Neural spine is flat & long directed backward.

(iv)Club shaped transverse process.

(v)Neural arch with superior articular process.

(vi)Two demifacets for articulation of head of a rib are present.

(5)Lumbar vertebra:

(i) Centrum acoelus.

(ii)Neural spine well developed.

(iii) Transverse process are thin and long.

(iv)Small accessory process present near the root of each transverse process.

(v) It is the largest vertebrae.

(6)Sacrum:

It is a triangular bone formed by fusion of 5 sacral vertebra.

(i)Fusion normally begins between 16 to 18 years of age and is completed by 30 yrs. of age.

(ii)Serves as strong foundation for pelvic girdle.

(iii)Sacrum with 4 pairs of anterior and posterior sacral foramina.

(iv)Lateral part of sacrum articulate with ilium of hip bone.

(v)Female sacrum is shorter,wider and more curved between S2 and S3 the male sacrum is longer,narrower,and less curved.

(vi)In birds some of the vertebrae are fused to form synsacrum.[Last thoracic +Lumbar +Sacral+One or two caudal].

(7)Coccyx:

(i)It is formed by fusion of four coccygeal vertebrae.

(ii)It is last section of backbone.

(iii)It is small triangular bone.

(iv)Two coccygeal cornua project upto articulate with sacral cornua.

(v) Rudimentary transverse process.

Thoracic basket